Medical needle assemblies

ABSTRACT

A safety arrangement for a medical needle ( 15 ) has a support ( 14 ) for carrying the mount end of the needle, and a sleeve ( 16 ) slidably mounted on the support ( 14 ) for movement from an initial position to a retracted position and then back to a protecting position where the sleeve ( 16 ) covers the tip ( 21 ) of the needle ( 15 ). A spring ( 32 ) urges the sleeve toward its protecting position and a blocking member ( 23 ) projects forwardly from the support ( 14 ) and is movable between non-blocking and blocking positions. In the non-blocking position the sleeve ( 16 ) is free to slide from its initial position to its retracted position. On movement of the sleeve to its protecting position, the blocking member ( 23 ) moves to lie between the support ( 14 ) and sleeve ( 16 ) to prevent subsequent movement of the sleeve away from its protecting position. A control mechanism ( 27 ) releases the blocking member ( 23 ) so that it may move from its non-blocking position to its blocking position, the mechanism ( 27 ) being controlled by movement of the sleeve ( 16 ) from its initial position at least partway towards its retracted position.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is the U.S. national stage application of InternationalApplication PCT/GB03/002689, filed Jun. 23, 2003, which internationalapplication was published on Dec. 31, 2003, as International PublicationWO 2004/000397 in the English language. The International Applicationclaims priority of Great Britain Patent Application No. 02 14452.5 filedJun. 22, 2002 and Great Britain Patent Application No. 03 02393.4 filedFeb. 3, 2003.

This invention relates to a safety arrangement for a medical needlehaving a mount end and a sharp tip, intended for penetration of a humanor animal body, or for other medical uses such as the penetration of apierceable membrane of an intravenous medication system. The inventionfurther relates to a safety arrangement including a medical needle asaforesaid, ready for use. For convenience, in the following all suchmedical uses will be described simply as the penetration of a body, eventhough specific embodiments may be intended for other medical uses.

Fluids of various kinds may be administered to a human or animal body bymeans of a hollow needle in conjunction with a source of the requiredfluid. For example, such a needle may be used in conjunction with asyringe holding a liquid drug, the needle being used to penetrate thebody at the site at which the drug is to be received. Equally, bodyfluids may be withdrawn by using a hollow needle which is used topenetrate the body until the tip is located at the site from which fluidis to be withdrawn.

A recognised hazard for clinicians and other persons using medicalneedles for the above described purposes is the risk of a so-calledneedle-stick injury—that is to say the accidental penetration of theclinician's skin by the needle. Prior to the use of the needle to supplya fluid to or to withdraw fluid from a body, this rarely presents muchof a problem, though once the needle has been used on a body, there is avery much higher risk of a serious consequence for the clinician. Duringuse of the needle to penetrate the body tissues of a patient, the needleis likely to become contaminated with various organisms and should aneedle-stick injury occur, these could infect the clinician.

There have been numerous proposals for protecting the sharp tip of aused needle, in order to reduce the risk of a needle-stick injuryfollowing use of the needle. Some proposals have actually increased thelikelihood of such an injury by virtue of the action which must beperformed to protect the tip, even if the risk thereafter is lessened.Despite all of the proposals which have previously been made, very fewhave achieved commercial success, nor has there been wide acceptance bythe medical industry. Many proposals are somewhat complex and involve asignificantly greater manufacturing cost, and so are unacceptable oneconomic grounds. Others are much more difficult to use as compared toan unprotected needle, and so are rejected by clinicians. Yet furtherproposals do not allow compliance with best practice protocols.

There is a significant demand for a protective device for use with aneedle, and which allows a clinician to use the needle in much the sameway as is done with an unprotected needle, but which can be manufacturedeconomically and which provides a high degree of protection againstneedle-stick injury. In this connection, it is highly preferred that thedevice operates fully automatically, without intervention by theclinician, to give a degree of protection to the needle tip before use,and after use wholly prevents access to the needle tip other than by adetermined attempt to override the protection. In this way, protectionmay be afforded not just to the clinician, but also to others who couldcome into a risky situation with used needles, such as waste disposaloperators, cleaners, and so on.

A device which protects a needle tip without an operator having toperform any extra step on withdrawing the needle from a body is usuallyreferred to as a passive protection device. This may be contrasted withan active protection device, where an operator is required to perform anextra step in order to protect a needle, following the withdrawal of theneedle from a body. The requirement to perform an extra step leaves theneedle unprotected for a longer period than with a passive protectiondevice and further the performance of that extra step exposes theoperator to a potentially hazardous situation, where needle-stickaccidents can occur.

Consequent upon research and development, the present invention hasevolved, to provide various forms of needle protection devices havingenhanced characteristics, but all employing the same underlying passiveprotection concept.

Accordingly, this invention provides a safety arrangement for a medicalneedle having a mount end and a sharp tip, which arrangement comprises:

-   -   a support adapted directly or indirectly to carry the mount end        of a needle so that the needle projects forwardly away        therefrom;    -   a sleeve mounted directly or indirectly on the support and being        slideable with respect thereto from an initial position where        the sleeve covers at least the greater part of a carried needle        to a retracted position where the tip of a carried needle and a        part of the needle back from its tip is exposed, and then to a        protecting position where the sleeve covers the needle tip and        at least part of the needle back from its tip;    -   resilient means arranged to urge the sleeve towards its        protecting position;    -   a blocking member at least a part of which projects forwardly        from the support, the blocking member being movable between a        non-blocking position where the blocking member extends        generally parallel to the needle axis and the sleeve may slide        to its retracted position and a blocking position where the        blocking member has moved from its non-blocking position so as        to be disposed between the support and a part of the sleeve,        thereby blocking movement of the sleeve away from its protecting        position; and    -   control means which releases the blocking member for movement        from its non-blocking position to its blocking position on        movement of the sleeve away from its initial position towards        its retracted position, so that on subsequent movement of the        sleeve to its protecting position the blocking member will        thereafter block movement of the sleeve away from its protecting        position.

It will be appreciated that the safety arrangement of this invention maybe provided with an integral medical needle, or may be adapted toreceive a medical needle shortly before being used to undertakepenetration of a body. Either way, a needle is initially protected atleast to some extent, though preferably wholly, by the sleeve, whichextends from the assembly support to overlie at least the greater partof the needle projecting from the support. The control member serves tohold the blocking member in such a position that the sleeve may be movedwith light pressure on its tip to its retracted position, where thatpart of the needle projecting beyond the housing is exposed. Suchpressure may be exerted by the skin of a patient or the pierceablemembrane of a medical apparatus as a clinician pushes the needle into abody and so the movement of the sleeve to its retracted positionrequires no separate action by the clinician.

On withdrawing the needle from a body, the safety arrangement operatesfully automatically and without the need for any operator intervention(i.e. it operates passively), to furnish a sleeve over the exposed partof a needle and to block that sleeve in a fully protecting position,from which the sleeve cannot be withdrawn short of destroying the safetyarrangement. Thus, an operator is automatically and effectivelyprotected against needle-stick injuries, following the completion of amedical procedure using the needle, when equipped with the safetyarrangement.

The support may define a connector for a cylindrical body such as asyringe, to extend co-axially with the needle. In one embodiment, thecylindrical body may serve slidably to support the sleeve when thesupport has been connected to the body. Alternatively, the support maybe defined by a rear wall of a tubular housing for the assembly and onor within which the sleeve is slidably carried.

The control means may include a releasable connection between twocomponents which are relatively movable along the axis of a needlecarried by the support, such that sufficient force releases theconnection and then allows the blocking member to move to its blockingposition, when the sleeve has moved to its protecting position. In apreferred embodiment, there is provided a control member mounted withinthe sleeve and the releasable connection is formed between the sleeveand the control member. In another embodiment, the releasable connectionis formed between a housing for the assembly and the blocking member,movement of the sleeve towards its retracted position releasing thatconnection to permit the blocking member to move towards the support,thereafter to perform the blocking action on movement of the sleeve toits protecting position.

In a preferred form of this invention, the assembly includes a tubularhousing having a rear wall which forms the needle support, the housingbeing open at its opposed end so that a supported needle may extend fromthe rear wall and project out of the opposed end. In such a case, thesleeve may be slidably mounted within the housing to surround asupported needle, the sleeve having a rear end nearer the rear wall ofthe housing and there being means to prevent the sleeve sliding off thehousing.

For this embodiment, the blocking member may have a base disposedbetween the rear end of the sleeve and the rear wall of the housing anda blocking section which extends from the base generally parallel to thelength of the sleeve and co-operable with the sleeve. A spring should bearranged to urge apart the sleeve and the blocking member. In thisarrangement:

-   -   with the sleeve in its initial position the control member is        disposed adjacent the rear end of the sleeve, engaged with the        blocking section of the blocking member;    -   on movement of the sleeve to its retracted position the control        member releasable connection is released so permitting the        control member to move into the sleeve, the control member        guiding the blocking section into the sleeve; and    -   on the sleeve subsequently moving to its protecting position        under the action of the spring, the base of the blocking member        is urged to bear on the housing rear wall and the blocking        section of the blocking member engages behind the rear end of        the sleeve, so preventing subsequent retraction of the sleeve        from its protecting position.

In a preferred form, the control means includes a control member whichis located within the sleeve, when the sleeve is in its initialposition. A releasable connection between the control member and thesleeve may comprise inter-engaged stops on both the outer surface of thecontrol member and the internal surface of the sleeve, which stops willoverride each other on the application of sufficient axial forcethereto. Alternatively, a simple frictional connection may be providedbetween the sleeve and the control member, whereby the control memberwill stay at any position within the sleeve unless a sufficient axialforce is applied thereto.

In the former case, the spring may act between the control member and aninternal flange formed within the tubular blocking member and so willact indirectly on the sleeve. In the latter case, the spring may beexternal to the blocking member and act directly on the sleeve.

Preferably, the sleeve is translucent and the control member is of ahigh visibility material. In this way, the control member can also actas a visual indicator so that a user may readily see whether theassembly has been used and so should be discarded, because the controlmember will be visible at the forward end of the sleeve. For anarrangement having a releasable connection with inter-engageable stops,there is the additional benefit of an audible “click” when the controlmember is moved forwardly by the spring.

In various preferred embodiments, the base of the blocking member iscircular and has a central hole through which the needle projects. Therearwardly directed face of that base may lie at an angle of a fewdegrees to the true radial plane and is opposed to a surface of thesupport, which surface lies in the true radial plane. The spring isarranged to urge the blocking member rearwardly, but so long as theblocking member is constrained by the control member or the sleeve tolie co-axial with or extending parallel to the axis of the needle, saidrearwardly directed face of the base will not lie flat against theradial surface of the support. Upon release of the blocking member, thespring urges the rearwardly directed face of the base to lie flatagainst the surface of the support, thus inclining the blocking memberto the axis of the needle. The blocking member is thus able to performits blocking function, to prevent the sleeve moving away from itsprotecting position.

This invention extends to an assembly of this invention as describedabove, in combination with a medical needle having a mount end and atip, the mount end of the needle being carried by the support, to extendtherefrom, through the blocking member and the sleeve.

Advantages possessed by various embodiments of the present invention arethat they afford wholly aseptic operations, a pre-requisite concerningthe introduction of a hollow-bore needle into a body. In preferredembodiments where the initial position and protecting position of thesleeve are the same, and so the needle tip is at all times covered otherthan when the needle is within a body, there is no possibility of theneedle being touched accidentally, either by a clinician or by someother component. If the sleeve unintentionally touches some other bodyto an extent sufficient to expose the needle tip, return of the sleeveto its fully forward position will lock the sleeve, so preventing use ofthe needle to perform an injection.

Further, the conventional practice of un-sheathing of a needle byremoving a cap is wholly eliminated. It is possible to damage a needletip by removing a cap and such damage leads to a more painful injection.

As the needle is covered at all times, other than during bodypenetration, there is the further advantage of a placebo effect, in thata patient will not see, and so not be frightened by, the needle. Thus,it is possible to give injections even with highly needle-phobicpatients.

By way of example only, several embodiments of this invention will nowbe described in detail, with reference to the accompanying drawings,showing the embodiments in various settings. In the drawings:

FIGS. 1A to 1E show the first embodiment, having an internal spring,with the sleeve moving from an initial position (FIG. 1A) to a fullywithdrawn position (FIG. 1C) and then to a protecting position (FIG.1E);

FIGS. 1F and 1G are detail views on an enlarged scale of part of theembodiment shown in FIG. 1A;

FIGS. 2A to 2E respectively correspond to FIGS. 1A to 1E, but of thesecond embodiment, having an external spring;

FIGS. 3A to 3D show the embodiment of FIG. 2 being used with an adapterin order to prevent the sleeve moving to its protecting position;

FIGS. 4A to 4D show the third embodiment, also having an externalspring, but arranged to be resettable, with the sleeve locked in theprotecting position (FIG. 4A) and then being reset, ready for reuse(FIG. 4D);

FIGS. 5A to 5E are similar to FIGS. 2A to 2E but of a fourth embodiment,having a spring external to the blocking member and being used with asyringe;

FIGS. 6A to 6E are again similar to FIGS. 2A to 2E but of a fifthembodiment not having a control member;

FIG. 6F is a view on an enlarged scale of part of the embodiment of FIG.6A;

FIGS. 7A to 7J show a sixth embodiment of safety arrangement, intendedfor use with a pre-filled syringe or a syringe to be filled from a vialof medicament;

FIGS. 8A to 8J show a seventh embodiment generally similar to that ofFIGS. 7A to 7J;

FIGS. 9A to 9E show an eighth embodiment intended for use with aninjection device intended to take a cartridge of medicament, suitablefor self-injection;

FIGS. 10A to 10C show an embodiment of packaging suitable for use withthe safety arrangement of FIG. 9;

FIGS. 11A to 11M show a ninth embodiment of safety arrangement, intendedfor use with a single-use throw-away syringe;

FIGS. 12A and 12B show a tenth embodiment of safety arrangement similarto that but more compact than the eighth embodiment of FIG. 9; and

FIGS. 13A to 13C show an eleventh embodiment of safety arrangement againfor use with an injection device intended to take a cartridge ofmedicament.

[Note: The suffix letter I is not used in the identification of theFigures to avoid confusion with the numeral 1]

In the following description of the embodiments of this invention, theterms front, forward, and so on are used to refer to that end of theneedle assembly whereat the sharp tip of the needle is located and alsoto the direction of insertion of the needle into a body. Conversely, theterms rear, rearwardly and so on are used to refer to the other end ofthe needle assembly, to which is connected other equipment such as asyringe or a blood collection system, and also to the direction ofremoval of a needle from a body.

Further, like components throughout the various embodiments are givenlike reference characters and will not be described in detail, for eachembodiment.

FIGS. 1A to 1G

The first embodiment of needle assembly of this invention shown in FIGS.1A to 1G comprises a tubular housing 10 assembled from a rear part 11and a front part 12, permanently secured together. The rear part 11includes a tapered socket 13 for receiving the hub of a syringe in themanner of a conventional taper-slip lock, thereby permitting theassembly to be mounted on a syringe ready for use. Internally, the rearpart 11 has a boss 14 which carries the mount end of a needle 15, in amanner well known in the art.

The syringe with which the embodiment is to be used may be a pre-filledsyringe, such that pre-attachment of the needle assembly immediatelyrenders the syringe ready for use. Rather than the taper slip lockshown, a threaded connector such as a Luer lock may be employed.Alternatively, the rear part may be configured for use with known formsof phlebotomy devices for collecting blood.

Slidably mounted in the forward region of the front part 12 is a tubularsleeve 16, the rear end of the sleeve having an external flange 17 whichengages a shoulder 18 formed internally within the front part 12. Thesleeve is thus constrained against further forward movement from theposition shown in FIGS. 1A and 1E, but may slide rearwardly as shown inFIGS. 1B and 1C. The forward end 19 of the sleeve 16 has an in-turnedlip 20 and the sleeve is of a sufficient length such that when itsflange 17 engages shoulder 18, the lip 20 is disposed beyond the sharptip 21 of the needle.

A tubular blocking member 23 surrounds the boss 14 and has a flange 24at its rear end and disposed adjacent a radial wall 25 of the rear part11 of the housing. The rearward facing surface of the flange 24 isnon-radial with respect to the axis of the blocking member and so thatface does not lie flat against the radial wall 25, as shown in FIG. 1G.The blocking member is slightly shorter than the distance between theradial wall 25 and the rear end of the sleeve, when the sleeve is fullyforward, as shown in FIG. 1A.

A control member 27 is located within the sleeve 16 and has a rearportion 28 which is receivable within the forward part of the blockingmember 23, the control member being profiled to limit rearward movementthereof into the blocking member. A releasable connection is formedbetween the control member 27 and the internal surface of the sleeve 16,shown in more detail in FIG. 1F, whereby the control member is heldagainst movement forwardly within the sleeve 16 until sufficient forceis applied to the sleeve in the rearward direction while the controlmember 27 is held stationary by abutting the forward end of the blockingmember and the flange 24 of the blocking member 23 abuts the rear wall25 of the housing 10. The releasable connection comprises an internalannular rib 29 engaged with an external preferably segmented annular rib30 on the control member, or conversely the rib 29 could be segmentedand the rib 30 continuous. Sufficient force on the sleeve will break theconnection by causing the sleeve rib 29 to ride over the control memberrib 30 whereafter the control member may slide freely within the sleevebetween the internal face of lip 20 and the sleeve rib 29.

A helical compression spring 32 is disposed within the blocking member23 and acts between the rear face of the control member 27 and anannular abutment 33 formed within the blocking member, just forward ofthe boss 14. The force exerted by the spring 32 is insufficient to breakthe connection between the control member and the sleeve when theassembly is in its initial position as shown in FIG. 1A. The rearwardprojection of rear portion 28 of the control member 27 is visible inFIG. 1G; this extended projection is intended to support the spring 32to remain essentially co-axial with the needle.

The operation of the assembly described above will now be described. Theinitial setting is with the assembly as shown in FIGS. 1A, 1F and 1Gwith the sleeve 16 fully forward and wholly protecting the needle 15;the control member 27 is connected to the sleeve and is urged forwardlyby the spring 32, transferring the spring force to the sleeve. In thisposition, flange 17 of the sleeve engages shoulder 18 of the front part12. The rear portion 28 of the control member is located in the blockingmember 23, so maintaining that member co-axial with the needle 15.

During initial rearward movement of the sleeve 16, for example by beingpressed against a body, the control member is maintained stationary bythe blocking member 23, in contact with the rear wall 25. If sufficientforce is applied to the sleeve 16 to break the connection, the sleevewill slide on to the blocking member 23. In addition, the control memberis released to move forwardly under the action of the spring, until thecontrol member engages the internal face of the sleeve lip 20. Thespring thus continues to urge the sleeve forwardly through the controlmember, but a force applied rearwardly to the sleeve greater than thespring force will allow continued progress of the sleeve, rearwardly.

FIG. 1C shows the sleeve in its extreme rearward position, with theneedle 15 projecting to its fullest extent, from the housing 10. Here,the rear portion 28 of the control member has once more entered theblocking member and the flange 17 of the sleeve abuts the flange 24 ofthe blocking member. Sufficient reduction on the rearward force on thesleeve (for example, by withdrawing the assembly away from a body) willallow the sleeve to move forwards under the action of the spring, asshown in FIG. 1D. On the sleeve moving to its protecting position shownin FIG. 1E, the blocking member 23 is free of the sleeve and so moves tothe position shown in that Figure, by virtue of the non-radial face ofits flange 24 engaging the radial wall 25 of the housing rear part 11,under the action of spring 32. When in its non-axial position, theblocking member blocks rearward movement of the sleeve away from itsprotecting position, so rendering safe the needle.

It will be appreciated that in clinical use, as the sleeve 16 comes intocontact with the pierceable membrane (e.g. the skin) of a body, thesleeve will automatically move rearwardly from its initial position,allowing penetration of the needle into the body. Further, once theconnection between the sleeve and the control member has been broken,the mechanism will automatically lock on the return of the sleeve to theposition shown in FIG. 1E. Thus, release of the sleeve from the positionshown in FIG. 1B but before the sleeve has moved to the position shownin FIG. 1C will still result in the protecting position of FIG. 1E beingachieved.

If the assembly is used in conjunction with a syringe to undertake drugdraw-up from a phial or ampoule into the syringe, this particularassembly must be discarded and a second assembly fitted to the syringe,to perform an injection. This is in fact the preferred clinicalprocedure since a lubricated and uncontaminated new needle should beused for body penetration. As well as protecting the needle, theassembly has the advantage of enforcing the “new-needle” clinicalprocedure, even should a clinician be disinclined to follow thespecified procedure.

The control member 27 is preferably made from a highly visible (e.g.strongly-coloured) plastics material, whereas the sleeve 16 ispreferably made of a translucent plastics material. Thus, a simpleinspection of the assembly will show whether it has been used, becausethe control member can be seen at the forward end of the sleeve, orwhether it is ready for use, because the control member is not presentwithin that part of the sleeve, beyond the front part 12 of the housing10 and irrespective of the position of the control member.

FIGS. 2A to 2E

The second embodiment of FIGS. 2A to 2E is generally similar to that ofFIGS. 1A to 1E, except that the connection between the control member 27and the sleeve 16 is differently configured, and a larger spring 35 isemployed, external to the blocking member 23. The spring acts betweenthe flange 24 of the blocking member and the rear face of the sleeve 16,so directly urging the sleeve forwardly, irrespective of the sleeveposition with respect to the housing 10.

A simple friction connection is employed between the control member 27and the sleeve 16, with sufficient friction to ensure the control memberremains stationary within the sleeve until sufficient force is appliedto the sleeve to overcome that friction. Then, the sleeve will moverearwardly while the control member 27 is held stationary by theblocking member and so is advanced relatively, within the sleeve.Subsequently, on forward movement of the sleeve under the action of thespring 35, the control member moves forward with the sleeve and so comesfree of the blocking member. Thereafter, this permits the blockingmember to perform its locking action as described with reference to FIG.1.

In this second embodiment, the amount of rearward movement of the sleeveneeded subsequently to result in the disengagement of the blockingmember 23 from the control member may be controlled by appropriateselection of the length of the rear portion 28 of the control member 27.With a short rear portion, only small rearward movement of the sleevewill result in an earlier disengagement of the blocking member.Conversely, with a long rear portion, a much greater rearward movementof the sleeve is required before subsequent forward movement of thesleeve disengages the control member from the blocking member.

The action with a long rear portion 28 may be advantageous where theassembly is to be used to perform drug draw-up from a phial or ampoule,before the same assembly is to be used to perform an injection, whereprocedures permit the same needle to be used for draw-up and subsequentinjection into a body—for example with the delivery of insulin. Thesleeve may appropriately be marked to show its maximum movement beforelocking will occur on subsequent release of the sleeve and provided thatmovement is not exceeded, then the assembly may be used firstly toundertake drug draw-up and secondly to perform an injection, fullyinserting the needle to its correct depth, whereafter the assembly willbe rendered safe.

The embodiment of FIG. 2 may be employed to give multiple injections,for example if one patient requires a plurality of intradermalinjections all in the same general area. This can be achieved by using atubular adapter 38 as shown in FIG. 3, in conjunction with the assemblyof FIG. 2 (or FIG. 1) together with a syringe 39 having a syringe body40 and a plunger 41. The needle assembly is fitted to the spigot 42 atthe front of the syringe body 40 and the adapter is then slipped overthe needle assembly and the syringe body (FIG. 3A). The adapter has anose profile 43 to receive the front of the sleeve 16 and, at its otherend, outwardly projecting finger grips 44.

The arrangement of FIG. 3 is used by the clinician holding the fingergrips 44 together with the head 45 of the plunger 41 and moving thesyringe body 40 deeper into the adapter 38, until the sleeve is fullyretracted, as shown in FIG. 3D. So long as pressure is maintainedbetween the finger grips 44 and the plunger head 45, the adapter 38 willhold the sleeve 16 in its retracted position. An increased force will berequired to drive the plunger 41 into the syringe 39 to deliver a druginto the body. A reduction in that increased force should maintain thesleeve in its retracted position, so allowing the re-siting of theneedle to another part of the body, for further injections. On releasingall pressure, spring 32 will move the sleeve 16 forwardly so fullyprotecting the needle before the syringe is removed from the adapter 38.

FIGS. 4A to 4D

This embodiment is a modified form of the second embodiment shown inFIGS. 2A to 2E. The modification is solely to the control member, whichis differently profiled as shown in FIG. 4A. The control member 50 isprovided with a counter-bore 51 at its forward end and the rear portion52 tapers towards its free end. Such a control member 50 allowsresetting of the assembly to a ready-to-use condition, from a lockedcondition.

FIG. 4A shows the assembly in its protecting (locked) condition, thiscorresponding to the setting of FIG. 2E. The mechanism may be reset bymeans of a tool having a fine tubular shaft 53, receivable through thelip 20 of the sleeve 16 and into the counter-bore 51 of control member50. Using this tool, the control member 50 may be pushed rearwardly,overcoming the friction between the control member 50 and the sleeve 16,until the control member re-enters the blocking member 23. The taperedprofile of the rear portion 52 lifts the control member out of itslocking position (FIG. 4B) and continued rearward movement of thecontrol member will bring the blocking member co-axial with the needle,as shown in FIG. 4C. Removal of the shaft 53 leaves the assembly reset,ready for use.

There is no risk to a clinician in using the tool to reset themechanism. There is no access to the needle tip until the shaft 53 hasbeen used to complete the resetting; during insertion of the shaft, thesleeve protects the needle and no manual access can be gained to theneedle tip.

FIGS. 5A to 5E

A fourth embodiment of this invention is shown in FIGS. 5A to 5E. Thisembodiment has a support wall 55 provided with a socket 56 to permit theassembly to be mounted on the hub 57 of a conventional syringe 58, thehub and socket together forming a conventional taper slip lock. Aconventional Luer lock could be used, instead. The syringe has acylindrical body 59 within which is mounted a plunger 60, to permitcharging of the syringe and discharging of a drug, through a needle 15supported on wall 55. A sleeve 62 has a forward portion 63 correspondingto sleeve 16 of the previous embodiments and a rearward portion 64formed integrally with the forward portion 63. The rearward portion hasa sufficient diameter to fit over the cylindrical body 59 of the syringeand is provided with an annular bead 65 at its free end, to stop thesleeve 62 coming off the wall 55.

Internally, the arrangement is essentially the same as that of theembodiment of FIG. 2, and so includes a blocking member 23, a controlmember 27 and a spring 35 external of the blocking member. The controlmember 27 is a frictional fit within the forward portion 63 of thesleeve 62 and so may be slid forwardly within the forward portion, asthe sleeve 62 is moved rearwardly. As previously, sufficient forwardmovement of the control member within the forward portion 63 allows theblocking member 23 to move to its inclined position shown in FIG. 5Eonce the sleeve 62 has moved to its protecting position, so thereafterpreventing retracting movement of the sleeve.

FIGS. 6 to 13

The embodiments of FIGS. 1 to 5 all employ a separate and movablecontrol member such as member 27 of FIG. 1, whereas the embodiments ofFIGS. 6 to 13 have no such control member. Rather, control of movementof the blocking member is achieved by alternative means, as will bedescribed.

FIGS. 6A to 6F

The fifth embodiment is shown in FIGS. 6A to 6F. This does not include acontrol member, but otherwise is similar to the second embodiment, shownin FIGS. 2A to 2E. In this fifth embodiment, at least one stop 70 isformed internally within the rear part 11 of the housing 10, adjacentbut spaced from the inner face of the radial wall 25. In addition, thesleeve 71, though generally similar to sleeve 16, has a shoulder 72 partway therealong, for engaging the blocking member 23 once the sleeve hasbeen moved sufficiently, rearwardly.

The or each such stop 70 is appropriately configured to hold theblocking member 23 away from the radial wall 25. The blocking member 23has such a length that when it bears on the stops 70 and the sleeve 71is in its initial position, the blocking member is located within therear end of the sleeve 71, as shown in FIG. 5A. In this position, theforce exerted by the spring 35 is insufficient to move the flange 24 ofthe blocking member over the or each stop 70.

On moving the sleeve rearwardly, the shoulder 72 of the sleeve will abutthe forward end of the blocking member 23. Thereafter, sufficientpressure on the sleeve will press the flange 24 of the blocking member23 over the stops 70, to engage the radial wall 25 of the housing rearpart 11.

From this point, operation is as with the second embodiment of FIG. 2.Movement of the assembly away from a body allows the sleeve 71 to moveforwardly under the action of the spring 35, and when fully forward, theblocking member 23 is inclined to the needle axis by virtue of theinter-engagement of the non-radial flange 24 of the blocking member withthe radial face of wall 25. The blocking member thus blocks subsequentmovement of the sleeve 71, towards its retracted position.

FIGS. 7A to 7J

The sixth embodiment is shown in FIGS. 7A to 7J. The safety arrangementis intended for use with a syringe having a body 80 fitted with a needle81 in the course of manufacture. The syringe has a plunger 82 with apiston 83 within the bore of the syringe, so that liquid may be drawninto the syringe through the needle 81 by withdrawing the plunger 82from its fully inserted position, the medicament subsequently beingexpelled through the needle 81 by depressing that plunger.

The plunger 82 has an X-shaped cross-section and differs from theplunger of a conventional syringe in that the outer edge of each arm ofthe X-shaped cross-section is provided with a protuberance 84, disposedapproximately one quarter of the way along the length of the plunger,from the piston end. In the region of each protuberance, the respectivearm has a through-slot 85 to enable radially inward movement of theprotuberances. The protuberances 84 define a stop position for theplunger on being moved into the bore by the application of axialpressure to the remote end 86 of the plunger. When the protuberancesreach the rear end of the syringe body, an increased force ismomentarily required to move the plunger deeper into the syringe body.

The safety arrangement for use with the syringe described abovecomprises a tubular support 87 having a bore in which the syringe body80 is snugly received. The needle is thus indirectly carried by thesupport, through the syringe itself. Formed within that bore is aninternal rib 88 which limits the movement of the syringe body into thebore. The part of the support 87 which overlies the syringe body has agreater wall thickness and slidably carries a sleeve 89. The forward end89A of the sleeve has an internal radial flange 90 formed with a centralhole 91 through which the needle 81 may project, the flange beingprovided with an upstand 92 which projects internally of the sleevetowards the syringe, the upstand having a relatively small arcuateextent, typically of only a few degrees. Partway along the length of thesleeve 89, an annular shoulder 83 is formed by a change in the internaland external diameters of the sleeve and between that shoulder 93 andthe flange 90, there is formed an inwardly-projecting annular rib 94(FIG. 7J). A further internal rib 95 (FIG. 7H) is formed at the rearwardend of the sleeve, over which an out-turned flange 96 at the rear end ofthe syringe body must ride to permit the sleeve to slide rearwardly fromthat position shown in FIGS. 7A, 7B and 7J.

A tubular blocking member 97 is slidably carried on the forward endportion of the support 87 and is urged forwardly by a helicalcompression spring 98, acting between the internal rib 88 of the supportand an internal flange 99 formed at the forward end of the blockingmember 97. Externally, the blocking member 97 has at its forward end anoutwardly-projecting flexible lip 100 slidable within the smallerdiameter portion of the sleeve 89 but movable over the internal rib 94of the sleeve only when an increased force is applied to the sleeve,relative to the blocking member. This is shown on an enlarged scale inFIG. 7K.

The starting position is shown in FIGS. 7A, 7B, 7J and 7K, with thesafety arrangement set ready for use, though the plunger will be fullyforward, to permit filling of the syringe. Alternatively, the syringecould be pre-filled, in which case the plunger will be set as shown, andthe filling step will be omitted.

If the syringe is to be filled, the nose part of a phial (not shown) ofmedicament is inserted into the hole 91 at the forward end of the sleeve89 and is pushed gently on to the needle 81, moving the sleeverearwardly with respect to the syringe by riding the further rib 95 ofthe sleeve over the out-turned flange 96 of the syringe body 80. Duringthis, the blocking member 97 moves rearwardly, simultaneously with thesleeve, against the action of spring 96. The combined force of thespring 96 acting on the blocking member 95 and the force required toride the further rib 95 over the out-turned flange 96 should be lessthan that required to move the lip 100 of the blocking member 97 overthe rib 94 of the sleeve. As such, during the phial-filling operation,the blocking member 97 remains with its lip 100 rearward of rib 94 ofthe sleeve (FIG. 7C).

Following charging of the syringe and then the removal of the phial, themechanism is ready for performing an injection. The operator applies agentle force on the remote end 86 of the plunger by applying a reactionto the sleeve 89 and this has the effect of moving the plunger forwardlyuntil the protuberances 84 are about to enter the syringe body, and alsoof pulling the sleeve rearwardly, to cause the needle 81 to project fromthe forward end of the sleeve. However, this can be achieved only byhaving the lip 100 of the blocking member 97 ride over the rib 94 of thesleeve 89 and so moving forwardly towards the flange 90 of the sleeve,as shown in FIG. 7D. Rearward movement of the sleeve may continue untilthe shoulder 93 engages that part of the support having a thickened wallthickness as shown in FIG. 7E. The needle 81 is then projecting beyondthe flange 90 to its greatest possible extent.

The assembly is used in this condition to perform an injection, firstlyby pushing the needle 81 into a body at the injection site and thenpushing the plunger fully forwardly, the protuberances 84 movinginwardly to permit this, as shown in FIG. 7F. The condition of FIG. 7Ecould instead be achieved by using the syringe with the connectedassembly to perform a stabbing motion against a body, so that theengagement of the flange 90 at the forward end of the sleeve moves thesleeve rearwardly with respect to the syringe.

On removing the syringe assembly from a body, by pulling rearwardly onthe plunger and releasing the sleeve, or by pulling on the sleeve andreleasing the plunger, the spring 98 will cause relative separation ofthe forward end of the sleeve and the support 87, the spring acting onthe flange 99 of the blocking member 97 to maintain contact between theforward end of the blocking member and upstand 92. Eventually, theseparation will be so great that the blocking member comes free of thesupport 87 and the spring force acting on the blocking member will allowit to cant over so that its axis lies at an acute angle to the axis ofthe sleeve and support member—FIG. 7G. When in this position, theblocking member 97 lies between the flange 90 of the sleeve and theforward end of the support 87 and so physically blocks subsequentrearward movement of the sleeve 89, with respect to the support andsyringe.

When in the setting of FIG. 7G, the needle is securely protected againstexposure. Having regard to the tubular nature of the blocking member 97,a very high force must be applied to the sleeve 89 in order to exposethe needle, in effect either destroying the sleeve or the blockingmember.

FIGS. 8A to 8H

The seventh embodiment is shown in FIGS. 8A to 8H. This seventhembodiment is generally similar to the sixth embodiment of FIGS. 7A to7J and like parts are given like reference numbers and will not bedescribed again in detail.

The seventh embodiment differs from the sixth embodiment in that thepart of the support 104 surrounding the syringe 80 does not have asignificantly increased wall thickness, though a step 105 is formedbetween forward and rearward parts of that support, in order to serve asa backstop for movement of the blocking member 97. At its rearward end,the support 104 has an increased internal diameter portion 106, topermit the accommodation therein of the out-turned flange 96 of asyringe, which may have an entirely conventional plunger not includingthe protuberances 84 of the sixth embodiment. That increased diameterpart 106 supports a tube 107 projecting forwardly coaxial with thesupport itself but with an annular space between the tube and thesupport. A sleeve 108 is slidably mounted within the tube 107, forwardmovement of the sleeve being limited by an external rib 109 around therear end of the sleeve and an internal shoulder 110 formed within thetube 107.

The sleeve has two axially-spaced internal ribs 111 and 1 12, each ofwhich can interact with the lip 100 of the blocking member 98 in agenerally similar manner to that described with respect to the sixthembodiment.

FIGS. 8A and 8B show the initial position, with a slight clearancebetween the rearward end of the blocking member 97 and the step 105 ofthe support 104. On loading a phial for the filling of the syringe,initially the sleeve moves rearwardly until the rear end face of theblocking member engages the step 105 (FIG. 8C) and continued rearwardpressure on the sleeve then allows the lip 100 of the blocking member toride over the first rib 111, then to move forwardly to engage the secondrib 112 (FIG. 8D). In this setting, the syringe may be filled from aphial and on releasing the phial from the syringe, the sleeve andblocking member will together move forwardly to the position shown inFIG. 8E, so covering the needle once more.

From this setting, operation is essentially as described in relation tothe sixth embodiment. Thus, the syringe assembly is used to make aninjection in the course of which the blocking member 97 moves fullyforwardly (FIG. 8F) and then further rearward movement of the sleeveallows the needle to project to its greatest possible extent (FIG. 8G),as the plunger is depressed (FIG. 8H). On withdrawing the needle, thesleeve 108 is moved forwardly under the action of the spring bearing onthe blocking member; finally the blocking member 97 comes free of thesupport 104 and is canted over (FIG. 8J) so as to provide a physicalblock between the support and the flange of the sleeve, as describedabove.

FIGS. 9A to 9E

The eighth embodiment is shown in FIGS. 9A to 9E and is a modified formof the sixth embodiment (FIGS. 7A to 7J) intended for use with aninjection device adapted to receive a cartridge of medicament. Forexample, the safety assembly of this eighth embodiment may be employedwith a medicament-dispensing “pen” intended for dispensing apre-selected but variable dose of insulin, for self-injection.

A support 115 directly carries a needle 116 the rear end of whichprojects into the space within the support 115, so that on fitting thesupport to an injection device carrying a cartridge of medicament, therear end of the needle will penetrate a membrane at the forward end ofthe cartridge. The needle 116 so thus communicates with the interior ofthe cartridge, for dispensing of the medicament.

A sleeve 117 is slidably mounted on the rearward part 118 of the support115 and has an in-turned lip 119 to prevent the sleeve moving forwardlywith respect to the support, from the position shown in FIGS. 9A and 9B.The forward end of the sleeve, its rib 94 and the blocking member 97 areall as described with respect to the sixth embodiment and are given likereference characters; these components will not be described furtherhere.

In the initial position shown in FIGS. 9A and 9B, the spring 98 is shownfully compressed but the force exerted thereby on the blocking member 97is insufficient to move the lip 100 of the blocking member over the rib94 of the sleeve. Equally, as discussed above, the support 115 cannotmove out of the sleeve by virtue of the in-turned lip 119 at the rearend of the sleeve.

When an injection (and typically a self-injection of insulin) is to bemade, the safety arrangement is mounted on the front end of an injectionpen, the appropriate dose is set and then the pen is used to perform astabbing motion on the selected body site. The flange 90 at the forwardend of the sleeve 117 serves to ensure that the needle 116 enters thebody essentially perpendicularly and the impact force on the body of theflange 90 at the forward end of the sleeve 117 serves to cause rib 94 toride over lip 100 of the blocking member. This allows the blockingmember 97 to move forwardly under the action of spring 98, as shown inFIG. 9C. From there, the operation is essentially as described abovewith reference to the sixth embodiment of FIG. 7. The injection isperformed with the assembly set as shown in FIG. 9D and, followingwithdrawal of the needle, the sleeve is blocked in its protectingposition as shown in FIG. 9E.

FIGS. 10A to 10C

Packaging for the eighth embodiment of FIG. 9, is illustrated in FIGS.10A to 10C. The safety device itself shown in these Figures is identicalto that of FIGS. 9A to 9E and will not be described again. Further, thesame reference numbers are used to designate the same components.

The packaging comprises a moulded plastics cylindrical tube 120 closedat one end by wall 121, and shaped to receive the safety assembly 122 ofFIGS. 9A and 9B in its initial condition as shown in FIGS. 10A and 10B.When so received, the tube 120 containing the assembly 122 may berendered sterile, using known techniques, and then sealed by a coverfoil 123 heat-sealed to a flange 124 around the open end of the tube120. That foil has a flap 125 to enable easy opening of the tube, whenthe assembly 122 is to be used.

As shown in the drawings, a cylindrical projection 126 upstands axiallyfrom the end wall 121 of the tube 120. That projection has such a lengththat when the assembly 122 is fully received in the tube 120, the innerend of the projection engages the blocking member 97 of the assembly andso prevents that blocking member moving forwardly under the action ofspring 98, notwithstanding the interengagement of the lip 100 with rib94 of the sleeve 117.

After opening the tube, the injection pen is pressed on to the assembly122 while still in the tube 120 and then the tube is pulled free of theassembly. Following use of the safety assembly to make an injection, thesleeve protects the needle as the blocking member prevents the sleevebeing withdrawn to expose the needle, as shown in FIG. 11C. The assemblymay then be inserted into the tube 120 but the other way round (that is,with the needle pointing towards the open end of the tube) and, havingregard to the draw of the tube, as the assembly is pushed fully home itforms a tight frictional fit within the tube. As such, it will beextremely difficult to withdraw the assembly once more and the needle isfully protected, for disposal.

FIGS. 11A to 11M

The ninth embodiment is shown in FIGS. 11A to 11M. This safetyarrangement is intended for use with a single-use luer-slip or luer-locksyringe having a syringe body 148 moulded from a plastics material andprovided with a luer-lock taper spigot 149 at its forward end, forreceiving a correspondingly profiled needle hub. Such syringes are wellknown in the art and are very widely used; following use of the syringe,it is thrown away with the needle still connected to the syringe.

The safety arrangement of this ninth embodiment has a support 128provided with a needle 129, the support defining a socket to receive theluer-lock spigot 149 at the forward end of the syringe 148. The support128 defines an outer cylindrical surface 130 on which a blocking member131 is slidably carried, a spring 132 acting between the support 128 andthe forward end of the blocking member 131. A two-part sleeve 134surrounds the support 128 and the blocking member 131, the rearward endportion 135 of the sleeve defining a cylindrical bore 136 within whichthe outer surface of the syringe body 148 is slidably receivable. Thetransition between that rearward end portion 135 and the central region137 of the sleeve forms a shoulder 138 against which both the support128 and the blocking member 131 abut, with the assembly in its initialposition as shown in FIGS. 11A and 11B.

The forward end portion 139 of the sleeve 134 has an enlarged diameterand carries a front sleeve part 140 configured similarly to the frontpart of the sleeve of the sixth and eighth embodiments. Thus, this frontpart 140 has a flange 90 at its forward end together with an upstand 92on that flange, and an annular rib 94 is formed internally, spacedrearwardly from the flange 90. Further, the forward end of the blockingmember 131 has a lip 100 to co-act with the rib 94, again as describedabove.

A protective tubular cap 142 is moulded integrally with the front part140 but is connected to the front part by relatively weak ribs aroundthe hole 91 in the flange 90. The cap projects internally into thesleeve by a small distance, as shown. The central hole in the flange 99of the blocking member is sufficiently large to permit the internallyprojecting part of the cap 142 to pass therethrough, and the blockingmember has an internal abutment 143 spaced rearwardly from the frontface of that member.

The initial position of the safety assembly, as supplied for use, is asshown in FIGS. 11A and 11B. It is connected to a syringe body 148 byinserting the forward end of the syringe into the bore 136 of the sleeve134 and engaging the spigot 149 with the support 128. As the syringebody moves deeper into the sleeve 134, the support 128 is also movedforwardly as shown in FIG. 11C, commencing the engagement of theluer-lock.

This continues until the support 128 abuts the rearward end of the cap142, within the sleeve 134 (FIG. 11D) and continued pressure on thesyringe then fully connects the Luer lock, between the syringe spigot149 and the support 128 (FIG. 11E). Depending upon the strength of theconnection between the cap 142 and the front part 140 of the sleeve, itmight be necessary to apply endwise pressure on the cap 142—for exampleby supporting the forward end of the cap 142 on a hard surface such as atable, and pressing the syringe body downwardly to engage the Luer lock.

Following full engagement of the spigot 149 with the support 128,release of the safety device returns it to its original setting, asshown in FIG. 11F. Then, the cap 142 may be broken away by applying asideways force thereto (FIG. 11G). During this operation, the needle iswithdrawn from the cap and so there is no risk of damage to the sharpend of the needle as the cap is broken away; this can be contrasted withthe usual arrangement employed with single-use syringes where great caremust be taken to move the cap axially, to avoid catching, and soburring, the sharp end of the needle.

The syringe is filled with an appropriate quantity of medicament bygently pressing a phial 145 on to the flange 90 at the forward end ofthe sleeve 134, so permitting the syringe and connected needle to movedeeper into the safety assembly. The needle penetrates the pierceablemembrane 146 of the phial, to permit the extraction of medicamenttherefrom by withdrawing the syringe plunger. Only light pressure isrequired to achieve this penetration, and so the lip 100 of the blockingmember 131 remains rearwardly of the rib 94 within the front part 140 ofthe sleeve (FIG. 11H).

Following filling of the syringe, the phial 145 is pulled away from theneedle, so allowing return of the safety assembly to its initialsetting, though without the cap 142 and so ready for use to perform aninjection (FIG. 11J).

From here, the operation of the safety assembly is much as has beendescribed above with reference to the previous embodiments. Onperforming a stabbing action to effect needle penetration into a body,the sleeve 134 initially moves rearwardly with respect to the support128, taking the blocking member 131 with it until the support engagesthe annular abutment 143 within the blocking member 131 (FIG. 11K).Continued rearward movement of the sleeve causes the lip 100 to rideover the rib 94 until maximum projection of the needle is achieved (FIG.11L), where the front of the blocking member 131 engages the upstand 92on the flange 90 of the sleeve 134. Finally, after completing theinjection and then withdrawing the needle from a body, the sleeve movesforwardly with respect to the syringe body, under the action of thespring 132 bearing on the blocking member. The flange 99 of the blockingmember remains in engagement with the flange 90 of the sleeve 134 sothat when the sleeve has moved fully forwardly with respect to thesyringe and connected support 128, the blocking member is free to cantover and fulfil its blocking function (FIG. 11M).

FIGS. 12A and 12B

FIGS. 12A and 12B show a modified form of the eighth embodiment, of FIG.9. This modified form has a shorter overall length, achieved byproviding a two-part support 155 the outer part 156 of which is foldedback on itself in order to provide a surrounding annular space 157within which the blocking member is slidably received. The rib 94 of thesleeve 117 is correspondingly nearer its flange 90. Thus, in the initialsetting, the blocking member is disposed forward of the front end of thesupport 155 and so the spring is not fully compressed. Further, thedistance the blocking member may move before engaging the upstand 92 ismuch reduced.

In other respects, the construction and operation of this modified formcorresponds to that of the eighth embodiment (FIG. 9) and so will not bedescribed in detail again, here.

FIGS. 13A to 13C

FIGS. 13A to 13C illustrate a tenth embodiment of this invention which,while generally similar to that of the eighth embodiment (FIG. 9)differs in one important detail. However, like parts with those of FIGS.9A to 9E are given like reference numbers.

The embodiment of FIGS. 13A to 13C does not include a rib 94 within thesleeve 89, so that the blocking member is held by spring 98 in a fullyforward position, when the assembly is in its initial setting (FIGS. 13Aand 13B). However, the blocking member is maintained coaxial with thesupport 115 and sleeve 117 by means of a slip ring 159, slidably carriedbut a light frictional fit on the support 115. The rearward end of theblocking member 97 is received within a counter-bore in the slip ring159.

On performing an injection, the sleeve 117 is moved rearwardly, takingthe slip ring 159 with it. Then, following completion of the injection,the sleeve and blocking member move forwardly once more but the slipring 159 remains in its rearmost position, on the support 115. Thus, onthe sleeve and blocking member moving fully forwardly, the blockingmember moves to its blocking position as shown in FIG. 13C, thusrendering the assembly safe with the sleeve blocked against movementaway from its protecting position.

In all of the above embodiments, the respective sleeves may be madetransparent, translucent or provided with a transparent or translucentwindow. By manufacturing the respective blocking member from astrongly-coloured material, the position of the blocking member withinthe sleeve will readily be discernible. Then, when the safety device hasbeen used and the blocking member is fully forward, this willimmediately be apparent on looking at the assembly.

1. A safety arrangement for a medical needle having a mount end and asharp tip, which arrangement comprises: a support adapted directly orindirectly to carry the mount end of a needle so that the needle has apart projecting forwardly away therefrom; a sleeve mounted directly orindirectly on the support and being slideable with respect thereto froman initial position where the sleeve fully covers the projecting part ofa carried needle to a retracted position where the tip of a carriedneedle and a part of the needle back from its tip is exposed, and thento a protecting position corresponding to the initial position and wherethe sleeve again covers the projecting part of the needle, saidprotecting position of the sleeve relative to said tip of the needlecorresponding to the initial position of the sleeve relative to saidtip; resilient means arranged to urge the sleeve towards its protectingposition; a tubular blocking member at least a part of which projectsforwardly from the support, the blocking member having a non-blockingposition where the blocking member is co-axial with the sleeve wherebythe sleeve is slidable with respect to the blocking member to saidretracted position, and the blocking member having a blocking positionwhere the axis of the blocking member lies at an acute angle to thesleeve and the blocking member is disposed between the support and apart of the sleeve, thereby blocking movement of the sleeve away fromsaid protecting position; and control means for maintaining the blockingmember co-axial with the sleeve during movement of the sleeve from itsinitial position to its retracted positions, but during movement of thesleeve from its retracted position said control means releases theblocking member for movement to its blocking position, and on subsequentmovement of the sleeve to its protecting position the blocking memberthereafter blocks movement of the sleeve away from its protectingposition.
 2. A safety arrangement as claimed in claim 1, wherein one endof the blocking member when in its blocking position co-operates with awall portion of one of the support and the sleeve to apply a turningmoment to the blocking member about an axis transverse to the length ofthe sleeve, so moving the second end of the blocking member to blockretracting movement of the sleeve.
 3. A safety arrangement as claimed inclaim 2, wherein one end of the blocking member has an off-set bossprojecting towards said adjacent wall portion of said one of the supportand the sleeve, whereby on the one end of blocking member being urgedtowards said adjacent wall portion, the off-set projection applies saidturning moment to the blocking member.
 4. A safety arrangement asclaimed in claim 2, wherein said wall portion has an off-set bossprojecting towards the adjacent one end of the blocking member, wherebyon said one end of the blocking member being urged towards said wallportion, the off-set projection applies said turning moment to theblocking member.
 5. A safety arrangement as claimed in claim 2, whereinone end of the blocking member presents a non-radial face to saidadjacent wall portion of said one of the support and the sleeve, wherebyon the one end of blocking member being urged towards said adjacent wallportion, the non-radial face applies said turning moment to the blockingmember.
 6. A safety arrangement as claimed in claim 2, wherein said wallportion presents a non-radial face to the adjacent one end of theblocking member, whereby on said one end of the blocking member beingurged towards said wall portion, the non-radial face applies saidturning moment to the blocking member.
 7. A safety arrangement asclaimed in claim 1, wherein said support includes a bore in which isreceivable a hypodermic syringe having said needle mounted on theforward end thereof such that when the syringe is received within saidbore, the needle projects forwardly into the sleeve.
 8. A safetyarrangement as claimed in claim 7, wherein the sleeve is slidablymounted externally on the support.
 9. A safety arrangement as claimed inclaim 7, wherein the sleeve is slidably received within a tubularcarrier, which carrier is mounted on said support.
 10. A safetyarrangement as claimed in claim 8, wherein the forward end of the sleevehas a generally radial inwardly directed flange having a centralaperture though which the tip of the needle may project when the sleeveis in its withdrawn position.
 11. A safety arrangement as claimed inclaim 7, wherein the blocking member is slidably carried on the sleevebut slides off the sleeve under the action of the resilient means tomove to its blocking position when released by the control means.
 12. Asafety arrangement as claimed in claim 1 for use with a hypodermicsyringe having a cylindrical body provided with a spigot at its forwardend for receiving a needle having a mounting hub at its rearward end,wherein said support includes a socket for receiving the spigot of ahypodermic syringe, the support being provided with a needle to projectforwardly from a mounted syringe with the needle in communication withthe spigot, and the sleeve being slideable on the external surface ofthe syringe body.
 13. A safety arrangement as claimed in claim 12,wherein the support has a greater diameter than the external diameter ofthe syringe body and the blocking member is slideable over said externaldiameter of the support.
 14. A safety arrangement as claimed in claim 1for use with an injection device adapted to hold a cartridge ofmedicament which device has a cylindrical body provided with a spigot atits forward end, wherein said support includes a socket for receivingthe spigot of the device, the support being provided with a needle toproject forwardly from the spigot with the rear end of the needle incommunication with a cartridge carried by the device, the support havingan external wall on which the sleeve is slidably supported.
 15. A safetyarrangement as claimed in claim 12, wherein the support has aforwardly-directed cylindrical surface of a smaller diameter than theexternal wall on which the sleeve is slideable, the blocking memberbeing slidably carried on said cylindrical surface.
 16. A safetyarrangement as claimed in claim 1, wherein the control means includes areleasable connection between the sleeve and the blocking member.
 17. Asafety arrangement as claimed in claim 16, wherein movement of thesleeve towards its retracted position releases the connection to permitthe blocking member to move towards its blocking position.
 18. A safetyarrangement as claimed in claim 17, wherein there is a secondaryreleasable connection between the sleeve and the blocking memberdisplaced axially from the first-mentioned releasable connection, thesecondary releasable connection being released by initial movement ofthe sleeve towards its withdrawn position, and the first-mentionedreleasable connection being released by further movement of the sleevetowards its withdrawn position so freeing the blocking member to move toits blocking position.
 19. A safety arrangement as claimed in claim 16,wherein the releasable connection comprises inter-engaged stopsrespectively on the mutually sliding surfaces of the blocking member andthe sleeve, which stops will over-ride each other on the application ofa sufficient axial force thereto.
 20. A safety arrangement as claimed inclaim 1, wherein there is a control member receivable within the sleeveand which initially supports the blocking member to lie substantiallycoaxial with the sleeve, there being a releasable connection between thesleeve and the control member which when released by movement of thesleeve away from its initial position permits the blocking member tomove to its blocking position on movement of the sleeve to itsprotecting position.
 21. A safety arrangement as claimed in claim 20,wherein the control member is located partly within the sleeve andpartly within the blocking member, when the sleeve is in its initialposition.
 22. A safety arrangement as claimed in claim 21, wherein thereleasable connection is formed directly between the outer surface ofthe control member and the internal surface of the sleeve.
 23. A safetyarrangement as claimed in claim 20, wherein the releasable connectioncomprises inter-engaged stops on both the outer surface of the controlmember and the internal surface of the sleeve, which stops willover-ride each other on the application of a sufficient axial forcethereto.
 24. A safety arrangement as claimed in claim 23, wherein theresilient means acts between the control member and an internal flangeformed within the blocking member and so indirectly on the sleevethrough the releasable connection.
 25. A safety arrangement as claimedin claim 24, wherein the sleeve is formed with an internal stop at itsforward end, the control member is a free sliding fit within the sleeve,and when the releasable connection is released, the control member movesforwardly under the action of the resilient means into engagement withthe internal stop.
 26. A safety arrangement as claimed in claim 20,wherein the releasable connection is formed by the control memberfitting in the sleeve in a frictionally-engaging manner.
 27. A safetyarrangement as claimed in claim 26, wherein the resilient meanssurrounds the blocking member to act directly between one end of thesleeve and the blocking member.
 28. A safety arrangement as claimed inclaim 26, wherein the control member includes an axial projection whichis received in the blocking member and is withdrawn therefrom bymovement of the sleeve towards the needle tip, drawing the controlmember therewith.
 29. A safety arrangement as claimed in claim 28,wherein the length of the axial projection is selected to control themaximum permissible movement of the sleeve towards its retractedposition before subsequent movement of the sleeve in the oppositedirection locks the sleeve against movement towards a retractedposition.
 30. A safety arrangement as claimed in claim 20, wherein thesupport defines a connector for a cylindrical body to extend coaxiallywith a needle connected thereto.
 31. A safety arrangement as claimed inclaim 30, wherein a connected cylindrical body serves slidably tosupport a sleeve moved from its initial position.
 32. A safetyarrangement as claimed in claim 30, wherein the support is defined by arear wall of a tubular housing on or within which the sleeve is slidablymounted.
 33. A safety arrangement as claimed in claim 1, wherein theresilient means comprises a helical coil spring.
 34. A safetyarrangement as claimed in claim 1 and in combination with a needle themount end of which is secured to the support, to project forwardlytherefrom.